/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing.plaf.basic;


import sun.swing.DefaultLookup;
import sun.swing.UIAction;

import java.awt.*;
import java.awt.event.*;

import java.beans.*;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.plaf.*;


/**
 * Implementation of ScrollBarUI for the Basic Look and Feel
 *
 * @version %I% %G%
 * @author Rich Schiavi
 * @author David Kloba
 * @author Hans Muller
 */
public class BasicScrollBarUI 
    extends ScrollBarUI implements LayoutManager, SwingConstants
{
    private static final int POSITIVE_SCROLL = 1;
    private static final int NEGATIVE_SCROLL = -1;

    private static final int MIN_SCROLL = 2;
    private static final int MAX_SCROLL = 3;

    // NOTE: DO NOT use this field directly, SynthScrollBarUI assumes you'll
    // call getMinimumThumbSize to access it.
    protected Dimension minimumThumbSize;
    protected Dimension maximumThumbSize;

    protected Color thumbHighlightColor;
    protected Color thumbLightShadowColor;
    protected Color thumbDarkShadowColor;
    protected Color thumbColor;
    protected Color trackColor;
    protected Color trackHighlightColor;

    protected JScrollBar scrollbar;
    protected JButton incrButton;
    protected JButton decrButton;
    protected boolean isDragging;
    protected TrackListener trackListener;
    protected ArrowButtonListener buttonListener;
    protected ModelListener modelListener;

    protected Rectangle thumbRect;
    protected Rectangle trackRect;

    protected int trackHighlight;

    protected static final int NO_HIGHLIGHT = 0;
    protected static final int DECREASE_HIGHLIGHT = 1;
    protected static final int INCREASE_HIGHLIGHT = 2;

    protected ScrollListener scrollListener;
    protected PropertyChangeListener propertyChangeListener; 
    protected Timer scrollTimer;

    private final static int scrollSpeedThrottle = 60; // delay in milli seconds

    /** True indicates a middle click will absolutely position the
     * scrollbar. */
    private boolean supportsAbsolutePositioning;

    /** Hint as to what width (when vertical) or height (when horizontal)
     * should be.
     */
    private int scrollBarWidth;

    private Handler handler;

    private boolean thumbActive;

    /**
     * Determine whether scrollbar layout should use cached value or adjusted
     * value returned by scrollbar's <code>getValue</code>.
     */
    private boolean useCachedValue = false;
    /**
     * The scrollbar value is cached to save real value if the view is adjusted.
     */
    private int scrollBarValue;

    /**
     * Distance between the increment button and the track. This may be a negative
     * number. If negative, then an overlap between the button and track will occur,
     * which is useful for shaped buttons.
     *
     * TODO This should be made protected in a feature release
     */
    private int incrGap;

    /**
     * Distance between the decrement button and the track. This may be a negative
     * number. If negative, then an overlap between the button and track will occur,
     * which is useful for shaped buttons.
     *
     * TODO This should be made protected in a feature release
     */
    private int decrGap;

    static void loadActionMap(LazyActionMap map) {
        map.put(new Actions(Actions.POSITIVE_UNIT_INCREMENT));
        map.put(new Actions(Actions.POSITIVE_BLOCK_INCREMENT));
        map.put(new Actions(Actions.NEGATIVE_UNIT_INCREMENT));
        map.put(new Actions(Actions.NEGATIVE_BLOCK_INCREMENT));
        map.put(new Actions(Actions.MIN_SCROLL));
        map.put(new Actions(Actions.MAX_SCROLL));
    }


    public static ComponentUI createUI(JComponent c)    {
        return new BasicScrollBarUI();
    }


    protected void configureScrollBarColors() 
    {
        LookAndFeel.installColors(scrollbar, "ScrollBar.background",
                                  "ScrollBar.foreground");
	thumbHighlightColor = UIManager.getColor("ScrollBar.thumbHighlight");
	thumbLightShadowColor = UIManager.getColor("ScrollBar.thumbShadow");
	thumbDarkShadowColor = UIManager.getColor("ScrollBar.thumbDarkShadow");
	thumbColor = UIManager.getColor("ScrollBar.thumb");
	trackColor = UIManager.getColor("ScrollBar.track");
	trackHighlightColor = UIManager.getColor("ScrollBar.trackHighlight");
    }


    public void installUI(JComponent c)   {
	scrollbar = (JScrollBar)c;
        thumbRect = new Rectangle(0, 0, 0, 0);
        trackRect = new Rectangle(0, 0, 0, 0);
	installDefaults();
	installComponents();
	installListeners();
	installKeyboardActions();
    }

    public void uninstallUI(JComponent c) {
	scrollbar = (JScrollBar)c;
	uninstallListeners();
	uninstallDefaults();
	uninstallComponents();
	uninstallKeyboardActions();
	thumbRect = null;
	scrollbar = null;
	incrButton = null;
	decrButton = null;
    }
    

    protected void installDefaults()
    {
	scrollBarWidth = UIManager.getInt("ScrollBar.width");
        if (scrollBarWidth <= 0) {
            scrollBarWidth = 16;
        }
	minimumThumbSize = (Dimension)UIManager.get("ScrollBar.minimumThumbSize");
	maximumThumbSize = (Dimension)UIManager.get("ScrollBar.maximumThumbSize");

	Boolean absB = (Boolean)UIManager.get("ScrollBar.allowsAbsolutePositioning");
	supportsAbsolutePositioning = (absB != null) ? absB.booleanValue() :
	                              false;

	trackHighlight = NO_HIGHLIGHT;
        if (scrollbar.getLayout() == null ||
                     (scrollbar.getLayout() instanceof UIResource)) {
            scrollbar.setLayout(this);
        }
	configureScrollBarColors();
        LookAndFeel.installBorder(scrollbar, "ScrollBar.border");
	LookAndFeel.installProperty(scrollbar, "opaque", Boolean.TRUE);

	scrollBarValue = scrollbar.getValue();

        incrGap = UIManager.getInt("ScrollBar.incrementButtonGap");
        decrGap = UIManager.getInt("ScrollBar.decrementButtonGap");

        // TODO this can be removed when incrGap/decrGap become protected
        // handle scaling for sizeVarients for special case components. The
        // key "JComponent.sizeVariant" scales for large/small/mini
        // components are based on Apples LAF
        String scaleKey = (String)scrollbar.getClientProperty(
                "JComponent.sizeVariant");
        if (scaleKey != null){
            if ("large".equals(scaleKey)){
                scrollBarWidth *= 1.15;
                incrGap *= 1.15;
                decrGap *= 1.15;
            } else if ("small".equals(scaleKey)){
                scrollBarWidth *= 0.857;
                incrGap *= 0.857;
                decrGap *= 0.714;
            } else if ("mini".equals(scaleKey)){
                scrollBarWidth *= 0.714;
                incrGap *= 0.714;
                decrGap *= 0.714;
            }
        }
    }


    protected void installComponents(){
        switch (scrollbar.getOrientation()) {
        case JScrollBar.VERTICAL:
            incrButton = createIncreaseButton(SOUTH);
            decrButton = createDecreaseButton(NORTH);
            break;
            
        case JScrollBar.HORIZONTAL:
            if (scrollbar.getComponentOrientation().isLeftToRight()) {    
                incrButton = createIncreaseButton(EAST);
                decrButton = createDecreaseButton(WEST);
            } else {
                incrButton = createIncreaseButton(WEST);
                decrButton = createDecreaseButton(EAST);
            }
            break;
        }
        scrollbar.add(incrButton);
        scrollbar.add(decrButton);
        // Force the children's enabled state to be updated.
	scrollbar.setEnabled(scrollbar.isEnabled());
    }

    protected void uninstallComponents(){
	scrollbar.remove(incrButton);
	scrollbar.remove(decrButton);
    }

  
    protected void installListeners(){
	trackListener = createTrackListener();
    	buttonListener = createArrowButtonListener();
    	modelListener = createModelListener();
	propertyChangeListener = createPropertyChangeListener();

	scrollbar.addMouseListener(trackListener);
	scrollbar.addMouseMotionListener(trackListener);
        scrollbar.getModel().addChangeListener(modelListener);
	scrollbar.addPropertyChangeListener(propertyChangeListener);
        scrollbar.addFocusListener(getHandler());

        if (incrButton != null) {
            incrButton.addMouseListener(buttonListener);
	}
        if (decrButton != null)	{
            decrButton.addMouseListener(buttonListener);
	}

	scrollListener = createScrollListener();
	scrollTimer = new Timer(scrollSpeedThrottle, scrollListener);
	scrollTimer.setInitialDelay(300);  // default InitialDelay?
    }


    protected void installKeyboardActions(){
        LazyActionMap.installLazyActionMap(scrollbar, BasicScrollBarUI.class,
                                           "ScrollBar.actionMap");

	InputMap inputMap = getInputMap(JComponent.WHEN_FOCUSED);
	SwingUtilities.replaceUIInputMap(scrollbar, JComponent.WHEN_FOCUSED,
					 inputMap);
	inputMap = getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
	SwingUtilities.replaceUIInputMap(scrollbar,
                   JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, inputMap);
    }

    protected void uninstallKeyboardActions(){
	SwingUtilities.replaceUIInputMap(scrollbar, JComponent.WHEN_FOCUSED,
					 null);
	SwingUtilities.replaceUIActionMap(scrollbar, null);
    }

    private InputMap getInputMap(int condition) {
	if (condition == JComponent.WHEN_FOCUSED) {
            InputMap keyMap = (InputMap)DefaultLookup.get(
                        scrollbar, this, "ScrollBar.focusInputMap");
            InputMap rtlKeyMap;

            if (scrollbar.getComponentOrientation().isLeftToRight() ||
                ((rtlKeyMap = (InputMap)DefaultLookup.get(scrollbar, this, "ScrollBar.focusInputMap.RightToLeft")) == null)) {
                return keyMap;
            } else {
                rtlKeyMap.setParent(keyMap);
                return rtlKeyMap;
            }
	}
	else if (condition == JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT) {
            InputMap keyMap = (InputMap)DefaultLookup.get(
                        scrollbar, this, "ScrollBar.ancestorInputMap");
            InputMap rtlKeyMap;

            if (scrollbar.getComponentOrientation().isLeftToRight() ||
                ((rtlKeyMap = (InputMap)DefaultLookup.get(scrollbar, this, "ScrollBar.ancestorInputMap.RightToLeft")) == null)) {
                return keyMap;
            } else {
                rtlKeyMap.setParent(keyMap);
                return rtlKeyMap;
            }
	}
	return null;
    }


    protected void uninstallListeners() {
	scrollTimer.stop();
	scrollTimer = null;

	if (decrButton != null){
	    decrButton.removeMouseListener(buttonListener);
	}
	if (incrButton != null){
	    incrButton.removeMouseListener(buttonListener);
	}
    
	scrollbar.getModel().removeChangeListener(modelListener);
	scrollbar.removeMouseListener(trackListener);
	scrollbar.removeMouseMotionListener(trackListener);
	scrollbar.removePropertyChangeListener(propertyChangeListener);
        scrollbar.removeFocusListener(getHandler());
        handler = null;
    }


    protected void uninstallDefaults(){
        LookAndFeel.uninstallBorder(scrollbar);
        if (scrollbar.getLayout() == this) {
            scrollbar.setLayout(null);
        }
    }


    private Handler getHandler() {
        if (handler == null) {
            handler = new Handler();
        }
        return handler;
    }

    protected TrackListener createTrackListener(){
	return new TrackListener();
    }

    protected ArrowButtonListener createArrowButtonListener(){
	return new ArrowButtonListener();
    }
    
    protected ModelListener createModelListener(){
	return new ModelListener();
    }

    protected ScrollListener createScrollListener(){
	return new ScrollListener();
    }
    
    protected PropertyChangeListener createPropertyChangeListener() {
	return getHandler();
    }

    private void updateThumbState(int x, int y) {
        Rectangle rect = getThumbBounds();

        setThumbRollover(rect.contains(x, y));
    }

    /**
     * Sets whether or not the mouse is currently over the thumb.
     *
     * @param active True indicates the thumb is currently active.
     * @since 1.5
     */
    protected void setThumbRollover(boolean active) {
        if (thumbActive != active) {
            thumbActive = active;
            scrollbar.repaint(getThumbBounds());
        }
    }

    /**
     * Returns true if the mouse is currently over the thumb.
     *
     * @return true if the thumb is currently active
     * @since 1.5
     */
    public boolean isThumbRollover() {
        return thumbActive;
    }

    public void paint(Graphics g, JComponent c) {
	paintTrack(g, c, getTrackBounds());		
	Rectangle thumbBounds = getThumbBounds();
	if (thumbBounds.intersects(g.getClipBounds())) {
	    paintThumb(g, c, thumbBounds);
	}
    }

        
    /**
     * A vertical scrollbar's preferred width is the maximum of 
     * preferred widths of the (non <code>null</code>)
     * increment/decrement buttons,
     * and the minimum width of the thumb. The preferred height is the 
     * sum of the preferred heights of the same parts.  The basis for 
     * the preferred size of a horizontal scrollbar is similar. 
     * <p>
     * The <code>preferredSize</code> is only computed once, subsequent
     * calls to this method just return a cached size.
     * 
     * @param c the <code>JScrollBar</code> that's delegating this method to us
     * @return the preferred size of a Basic JScrollBar
     * @see #getMaximumSize
     * @see #getMinimumSize
     */
    public Dimension getPreferredSize(JComponent c) {
	return (scrollbar.getOrientation() == JScrollBar.VERTICAL)
	    ? new Dimension(scrollBarWidth, 48)
	    : new Dimension(48, scrollBarWidth);
    }


    /**
     * @param c The JScrollBar that's delegating this method to us.
     * @return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE);
     * @see #getMinimumSize
     * @see #getPreferredSize
     */
    public Dimension getMaximumSize(JComponent c) {
        return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE);
    }
    	    
    protected JButton createDecreaseButton(int orientation)  {
        return new BasicArrowButton(orientation, 
				    UIManager.getColor("ScrollBar.thumb"),
				    UIManager.getColor("ScrollBar.thumbShadow"),
				    UIManager.getColor("ScrollBar.thumbDarkShadow"),
				    UIManager.getColor("ScrollBar.thumbHighlight"));
    }

    protected JButton createIncreaseButton(int orientation)  {
        return new BasicArrowButton(orientation,
				    UIManager.getColor("ScrollBar.thumb"),
				    UIManager.getColor("ScrollBar.thumbShadow"),
				    UIManager.getColor("ScrollBar.thumbDarkShadow"),
				    UIManager.getColor("ScrollBar.thumbHighlight"));
    }
          		  

    protected void paintDecreaseHighlight(Graphics g)
    {
	Insets insets = scrollbar.getInsets();
	Rectangle thumbR = getThumbBounds();
	g.setColor(trackHighlightColor);

	if (scrollbar.getOrientation() == JScrollBar.VERTICAL) {
            //paint the distance between the start of the track and top of the thumb
	    int x = insets.left;
	    int y = trackRect.y;
	    int w = scrollbar.getWidth() - (insets.left + insets.right);
	    int h = thumbR.y - y;
	    g.fillRect(x, y, w, h);
	} 
	else	{
            //if left-to-right, fill the area between the start of the track and
            //the left edge of the thumb. If right-to-left, fill the area between
            //the end of the thumb and end of the track.
	    int x, w;
	    if (scrollbar.getComponentOrientation().isLeftToRight()) {
		x = trackRect.x;
		w = thumbR.x - x;
	    } else {
		x = thumbR.x + thumbR.width;
		w = trackRect.x + trackRect.width - x;
	    }
	    int y = insets.top;
	    int h = scrollbar.getHeight() - (insets.top + insets.bottom);
	    g.fillRect(x, y, w, h);
	}
    }      
	

    protected void paintIncreaseHighlight(Graphics g)
    {
	Insets insets = scrollbar.getInsets();
	Rectangle thumbR = getThumbBounds();
	g.setColor(trackHighlightColor);

	if (scrollbar.getOrientation() == JScrollBar.VERTICAL) {
            //fill the area between the bottom of the thumb and the end of the track.
	    int x = insets.left;
	    int y = thumbR.y + thumbR.height;
	    int w = scrollbar.getWidth() - (insets.left + insets.right);
	    int h = trackRect.y + trackRect.height - y;
	    g.fillRect(x, y, w, h);
	} 
	else {
            //if left-to-right, fill the area between the right of the thumb and the
            //end of the track. If right-to-left, then fill the area to the left of
            //the thumb and the start of the track.
	    int x, w;
	    if (scrollbar.getComponentOrientation().isLeftToRight()) {
		x = thumbR.x + thumbR.width;
		w = trackRect.x + trackRect.width - x;
	    } else {
		x = trackRect.x;
		w = thumbR.x - x;
	    }
	    int y = insets.top;
	    int h = scrollbar.getHeight() - (insets.top + insets.bottom);
	    g.fillRect(x, y, w, h);
	}
    }      


    protected void paintTrack(Graphics g, JComponent c, Rectangle trackBounds)  
    {
        g.setColor(trackColor);
        g.fillRect(trackBounds.x, trackBounds.y, trackBounds.width, trackBounds.height);	

	if(trackHighlight == DECREASE_HIGHLIGHT)	{
	    paintDecreaseHighlight(g);
	} 
	else if(trackHighlight == INCREASE_HIGHLIGHT)		{
	    paintIncreaseHighlight(g);
	}
    }

	
    protected void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds)  
    {
	if(thumbBounds.isEmpty() || !scrollbar.isEnabled())	{
	    return;
	}

        int w = thumbBounds.width;
        int h = thumbBounds.height;		

	g.translate(thumbBounds.x, thumbBounds.y);

	g.setColor(thumbDarkShadowColor);
	g.drawRect(0, 0, w-1, h-1);    
	g.setColor(thumbColor);
	g.fillRect(0, 0, w-1, h-1);
        
        g.setColor(thumbHighlightColor);
        g.drawLine(1, 1, 1, h-2);
        g.drawLine(2, 1, w-3, 1);
        
        g.setColor(thumbLightShadowColor);
        g.drawLine(2, h-2, w-2, h-2);
        g.drawLine(w-2, 1, w-2, h-3);

	g.translate(-thumbBounds.x, -thumbBounds.y);
    }


    /** 
     * Return the smallest acceptable size for the thumb.  If the scrollbar
     * becomes so small that this size isn't available, the thumb will be
     * hidden.  
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a shared static constant.
     *
     * @return The smallest acceptable size for the thumb.
     * @see #getMaximumThumbSize
     */
    protected Dimension getMinimumThumbSize() { 
	return minimumThumbSize;
    }

    /** 
     * Return the largest acceptable size for the thumb.  To create a fixed 
     * size thumb one make this method and <code>getMinimumThumbSize</code> 
     * return the same value.
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a shared static constant.
     *
     * @return The largest acceptable size for the thumb.
     * @see #getMinimumThumbSize
     */
    protected Dimension getMaximumThumbSize()	{ 
	return maximumThumbSize;
    }


    /*
     * LayoutManager Implementation
     */

    public void addLayoutComponent(String name, Component child) {}
    public void removeLayoutComponent(Component child) {}
    
    public Dimension preferredLayoutSize(Container scrollbarContainer)  {
        return getPreferredSize((JComponent)scrollbarContainer);
    }
    
    public Dimension minimumLayoutSize(Container scrollbarContainer) {
        return getMinimumSize((JComponent)scrollbarContainer);
    }
    
    private int getValue(JScrollBar sb) {
	return (useCachedValue) ? scrollBarValue : sb.getValue();
    }

    protected void layoutVScrollbar(JScrollBar sb)  
    {
        Dimension sbSize = sb.getSize();
        Insets sbInsets = sb.getInsets();

	/*
	 * Width and left edge of the buttons and thumb.
	 */
	int itemW = sbSize.width - (sbInsets.left + sbInsets.right);
	int itemX = sbInsets.left;
        
        /* Nominal locations of the buttons, assuming their preferred
	 * size will fit.
	 */
        boolean squareButtons = DefaultLookup.getBoolean(
            scrollbar, this, "ScrollBar.squareButtons", false);
        int decrButtonH = squareButtons ? itemW :
                          decrButton.getPreferredSize().height;
        int decrButtonY = sbInsets.top;
        
        int incrButtonH = squareButtons ? itemW :
                          incrButton.getPreferredSize().height;
        int incrButtonY = sbSize.height - (sbInsets.bottom + incrButtonH);
        
        /* The thumb must fit within the height left over after we
	     * subtract the preferredSize of the buttons and the insets
	     * and the gaps
	     */
        int sbInsetsH = sbInsets.top + sbInsets.bottom;
        int sbButtonsH = decrButtonH + incrButtonH;
        int gaps = decrGap + incrGap;
        float trackH = sbSize.height - (sbInsetsH + sbButtonsH) - gaps;
        
        /* Compute the height and origin of the thumb.   The case
	 * where the thumb is at the bottom edge is handled specially 
	 * to avoid numerical problems in computing thumbY.  Enforce
	 * the thumbs min/max dimensions.  If the thumb doesn't
	 * fit in the track (trackH) we'll hide it later.
	 */
	float min = sb.getMinimum();
	float extent = sb.getVisibleAmount();
	float range = sb.getMaximum() - min;
	float value = getValue(sb);

        int thumbH = (range <= 0) 
	    ? getMaximumThumbSize().height : (int)(trackH * (extent / range));
	thumbH = Math.max(thumbH, getMinimumThumbSize().height);
	thumbH = Math.min(thumbH, getMaximumThumbSize().height);
        
	int thumbY = incrButtonY - incrGap - thumbH;
	if (value < (sb.getMaximum() - sb.getVisibleAmount())) {
	    float thumbRange = trackH - thumbH;
	    thumbY = (int)(0.5f + (thumbRange * ((value - min) / (range - extent))));
	    thumbY +=  decrButtonY + decrButtonH + decrGap;
	}

        /* If the buttons don't fit, allocate half of the available 
	 * space to each and move the lower one (incrButton) down.
	 */
        int sbAvailButtonH = (sbSize.height - sbInsetsH);
        if (sbAvailButtonH < sbButtonsH) {
            incrButtonH = decrButtonH = sbAvailButtonH / 2;
            incrButtonY = sbSize.height - (sbInsets.bottom + incrButtonH);
        }
        decrButton.setBounds(itemX, decrButtonY, itemW, decrButtonH);
        incrButton.setBounds(itemX, incrButtonY, itemW, incrButtonH);

	/* Update the trackRect field.
	 */	
	int itrackY = decrButtonY + decrButtonH + decrGap;
	int itrackH = incrButtonY - incrGap - itrackY;
	trackRect.setBounds(itemX, itrackY, itemW, itrackH);
	
	/* If the thumb isn't going to fit, zero it's bounds.  Otherwise
	 * make sure it fits between the buttons.  Note that setting the
	 * thumbs bounds will cause a repaint.
	 */
	if(thumbH >= (int)trackH)	{
	    setThumbBounds(0, 0, 0, 0);
	}
	else {
	    if ((thumbY + thumbH) > incrButtonY - incrGap) {
		thumbY = incrButtonY - incrGap - thumbH;
	    }
	    if (thumbY  < (decrButtonY + decrButtonH + decrGap)) {
		thumbY = decrButtonY + decrButtonH + decrGap + 1;
	    }
	    setThumbBounds(itemX, thumbY, itemW, thumbH);
	}
    }
    

    protected void layoutHScrollbar(JScrollBar sb)  
    {
        Dimension sbSize = sb.getSize();
        Insets sbInsets = sb.getInsets();
        
	/* Height and top edge of the buttons and thumb.
	 */
	int itemH = sbSize.height - (sbInsets.top + sbInsets.bottom);
	int itemY = sbInsets.top;

        boolean ltr = sb.getComponentOrientation().isLeftToRight();

        /* Nominal locations of the buttons, assuming their preferred
	 * size will fit.
	 */
        boolean squareButtons = DefaultLookup.getBoolean(
            scrollbar, this, "ScrollBar.squareButtons", false);
        int leftButtonW = squareButtons ? itemH :
                          decrButton.getPreferredSize().width;
        int rightButtonW = squareButtons ? itemH :
                          incrButton.getPreferredSize().width;
        if (!ltr) {
            int temp = leftButtonW;
            leftButtonW = rightButtonW;
            rightButtonW = temp;
        }
        int leftButtonX = sbInsets.left;        
        int rightButtonX = sbSize.width - (sbInsets.right + rightButtonW);
        int leftGap = ltr ? decrGap : incrGap;
        int rightGap = ltr ? incrGap : decrGap;

        /* The thumb must fit within the width left over after we
	     * subtract the preferredSize of the buttons and the insets
	     * and the gaps
	     */
        int sbInsetsW = sbInsets.left + sbInsets.right;
        int sbButtonsW = leftButtonW + rightButtonW;
        float trackW = sbSize.width - (sbInsetsW + sbButtonsW) - (leftGap + rightGap);
        
        /* Compute the width and origin of the thumb.  Enforce
	 * the thumbs min/max dimensions.  The case where the thumb 
	 * is at the right edge is handled specially to avoid numerical 
	 * problems in computing thumbX.  If the thumb doesn't
	 * fit in the track (trackH) we'll hide it later.
	 */
        float min = sb.getMinimum();
        float max = sb.getMaximum();
        float extent = sb.getVisibleAmount();
        float range = max - min;
        float value = getValue(sb);

        int thumbW = (range <= 0) 
	    ? getMaximumThumbSize().width : (int)(trackW * (extent / range));
        thumbW = Math.max(thumbW, getMinimumThumbSize().width);
        thumbW = Math.min(thumbW, getMaximumThumbSize().width);
        
	int thumbX = ltr ? rightButtonX - rightGap - thumbW : leftButtonX + leftButtonW + leftGap;
	if (value < (max - sb.getVisibleAmount())) {
	    float thumbRange = trackW - thumbW;
            if( ltr ) {
                thumbX = (int)(0.5f + (thumbRange * ((value - min) / (range - extent))));
            } else {
                thumbX = (int)(0.5f + (thumbRange * ((max - extent - value) / (range - extent))));
            }
	    thumbX +=  leftButtonX + leftButtonW + leftGap;
	}

        /* If the buttons don't fit, allocate half of the available 
         * space to each and move the right one over.
         */
        int sbAvailButtonW = (sbSize.width - sbInsetsW);
        if (sbAvailButtonW < sbButtonsW) {
            rightButtonW = leftButtonW = sbAvailButtonW / 2;
            rightButtonX = sbSize.width - (sbInsets.right + rightButtonW + rightGap);
        }
        
        (ltr ? decrButton : incrButton).setBounds(leftButtonX, itemY, leftButtonW, itemH);
        (ltr ? incrButton : decrButton).setBounds(rightButtonX, itemY, rightButtonW, itemH);

	/* Update the trackRect field.
	 */	
	int itrackX = leftButtonX + leftButtonW + leftGap;
	int itrackW = rightButtonX - rightGap - itrackX;
	trackRect.setBounds(itrackX, itemY, itrackW, itemH);

	/* Make sure the thumb fits between the buttons.  Note 
	 * that setting the thumbs bounds causes a repaint.
	 */
	if (thumbW >= (int)trackW) {
	    setThumbBounds(0, 0, 0, 0);
	}
	else {
	    if (thumbX + thumbW > rightButtonX - rightGap) {
		thumbX = rightButtonX - rightGap - thumbW;
	    }
	    if (thumbX  < leftButtonX + leftButtonW + leftGap) {
		thumbX = leftButtonX + leftButtonW + leftGap + 1;
	    }
	    setThumbBounds(thumbX, itemY, thumbW, itemH);
	}
    }

    public void layoutContainer(Container scrollbarContainer) 
    {
	/* If the user is dragging the value, we'll assume that the 
	 * scrollbars layout is OK modulo the thumb which is being 
	 * handled by the dragging code.
	 */
	if (isDragging) {
	    return;
	}

        JScrollBar scrollbar = (JScrollBar)scrollbarContainer;
        switch (scrollbar.getOrientation()) {
        case JScrollBar.VERTICAL:
            layoutVScrollbar(scrollbar);
            break;
            
        case JScrollBar.HORIZONTAL:
            layoutHScrollbar(scrollbar);
            break;
        }
    }


    /**
     * Set the bounds of the thumb and force a repaint that includes
     * the old thumbBounds and the new one.
     *
     * @see #getThumbBounds
     */
    protected void setThumbBounds(int x, int y, int width, int height)
    {
	/* If the thumbs bounds haven't changed, we're done.
	 */
	if ((thumbRect.x == x) && 
	    (thumbRect.y == y) && 
	    (thumbRect.width == width) && 
	    (thumbRect.height == height)) {
	    return;
	}

	/* Update thumbRect, and repaint the union of x,y,w,h and 
	 * the old thumbRect.
	 */
	int minX = Math.min(x, thumbRect.x);
	int minY = Math.min(y, thumbRect.y);
	int maxX = Math.max(x + width, thumbRect.x + thumbRect.width);
	int maxY = Math.max(y + height, thumbRect.y + thumbRect.height);

	thumbRect.setBounds(x, y, width, height);
	scrollbar.repaint(minX, minY, maxX - minX, maxY - minY);

        // Once there is API to determine the mouse location this will need
        // to be changed.
        setThumbRollover(false);
    }


    /**
     * Return the current size/location of the thumb.
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a reference to the actual rectangle, not a copy.
     *
     * @return The current size/location of the thumb.
     * @see #setThumbBounds
     */
    protected Rectangle getThumbBounds() {
	return thumbRect;
    }


    /**
     * Returns the current bounds of the track, i.e. the space in between
     * the increment and decrement buttons, less the insets.  The value
     * returned by this method is updated each time the scrollbar is
     * laid out (validated).
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a reference to the actual rectangle, not a copy.
     *
     * @return the current bounds of the scrollbar track
     * @see #layoutContainer
     */
    protected Rectangle getTrackBounds() {
	return trackRect;
    }

    /*
     * Method for scrolling by a block increment.
     * Added for mouse wheel scrolling support, RFE 4202656.
     */
    static void scrollByBlock(JScrollBar scrollbar, int direction) {
        // This method is called from BasicScrollPaneUI to implement wheel
        // scrolling, and also from scrollByBlock().
	    int oldValue = scrollbar.getValue();
	    int blockIncrement = scrollbar.getBlockIncrement(direction);
	    int delta = blockIncrement * ((direction > 0) ? +1 : -1);
	    int newValue = oldValue + delta;
	    
	    // Check for overflow.
	    if (delta > 0 && newValue < oldValue) {
		newValue = scrollbar.getMaximum();
	    }
	    else if (delta < 0 && newValue > oldValue) {
		newValue = scrollbar.getMinimum();
	    }

	    scrollbar.setValue(newValue);			
    }

    protected void scrollByBlock(int direction)
    {
        scrollByBlock(scrollbar, direction);
	    trackHighlight = direction > 0 ? INCREASE_HIGHLIGHT : DECREASE_HIGHLIGHT;
	    Rectangle dirtyRect = getTrackBounds();
	    scrollbar.repaint(dirtyRect.x, dirtyRect.y, dirtyRect.width, dirtyRect.height);
    }
    
    /*
     * Method for scrolling by a unit increment.
     * Added for mouse wheel scrolling support, RFE 4202656.
     *
     * If limitByBlock is set to true, the scrollbar will scroll at least 1
     * unit increment, but will not scroll farther than the block increment.
     * See BasicScrollPaneUI.Handler.mouseWheelMoved().
     */
    static void scrollByUnits(JScrollBar scrollbar, int direction,
                              int units, boolean limitToBlock) {
        // This method is called from BasicScrollPaneUI to implement wheel
        // scrolling, as well as from scrollByUnit().
        int delta;
        int limit = -1;

        if (limitToBlock) {
            if (direction < 0) {
                limit = scrollbar.getValue() -
                                         scrollbar.getBlockIncrement(direction);
            }
            else {
                limit = scrollbar.getValue() +
                                         scrollbar.getBlockIncrement(direction);
            }
        }

        for (int i=0; i<units; i++) {
            if (direction > 0) {
                delta = scrollbar.getUnitIncrement(direction);
            }
            else {
                delta = -scrollbar.getUnitIncrement(direction);
            }

            int oldValue = scrollbar.getValue();
            int newValue = oldValue + delta;

            // Check for overflow.
            if (delta > 0 && newValue < oldValue) {
                newValue = scrollbar.getMaximum();
            }
            else if (delta < 0 && newValue > oldValue) {
                newValue = scrollbar.getMinimum();
            }
            if (oldValue == newValue) {
                break;
            }

            if (limitToBlock && i > 0) {
                assert limit != -1;
                if ((direction < 0 && newValue < limit) ||
                    (direction > 0 && newValue > limit)) {
                    break;
                }
            }
            scrollbar.setValue(newValue);
        }
    }

    protected void scrollByUnit(int direction)	{
        scrollByUnits(scrollbar, direction, 1, false);
    }

    /**
     * Indicates whether the user can absolutely position the thumb with
     * a mouse gesture (usually the middle mouse button).
     *
     * @return true if a mouse gesture can absolutely position the thumb
     * @since 1.5
     */
    public boolean getSupportsAbsolutePositioning() {
	return supportsAbsolutePositioning;
    }

    /**
     * A listener to listen for model changes.
     *
     */
    protected class ModelListener implements ChangeListener {
        public void stateChanged(ChangeEvent e) {
	    if (!useCachedValue) {
		scrollBarValue = scrollbar.getValue();
	    }
	    layoutContainer(scrollbar);
	    useCachedValue = false;
        }
    }


    /**
     * Track mouse drags.
     */
    protected class TrackListener
        extends MouseAdapter implements MouseMotionListener
    {
	protected transient int offset;
	protected transient int currentMouseX, currentMouseY;
 	private transient int direction = +1;
		
        public void mouseReleased(MouseEvent e)
        {
            if (isDragging) {
                updateThumbState(e.getX(), e.getY());
            }
	    if (SwingUtilities.isRightMouseButton(e) ||
		(!getSupportsAbsolutePositioning() &&
		 SwingUtilities.isMiddleMouseButton(e)))
		return;
	    if(!scrollbar.isEnabled())
		return;

	    Rectangle r = getTrackBounds();
	    scrollbar.repaint(r.x, r.y, r.width, r.height);

	    trackHighlight = NO_HIGHLIGHT;
	    isDragging = false;
	    offset = 0;
	    scrollTimer.stop();
	    useCachedValue = true;
	    scrollbar.setValueIsAdjusting(false);
	}
		

        /**
	 * If the mouse is pressed above the "thumb" component
	 * then reduce the scrollbars value by one page ("page up"), 
	 * otherwise increase it by one page.  If there is no 
	 * thumb then page up if the mouse is in the upper half
	 * of the track.
	 */
        public void mousePressed(MouseEvent e) 
	{
	    if (SwingUtilities.isRightMouseButton(e) ||
		(!getSupportsAbsolutePositioning() &&
		 SwingUtilities.isMiddleMouseButton(e)))
		return;
	    if(!scrollbar.isEnabled())
		return;

	    if (!scrollbar.hasFocus() && scrollbar.isRequestFocusEnabled()) {
		scrollbar.requestFocus();
	    }

	    useCachedValue = true;
	    scrollbar.setValueIsAdjusting(true);

            currentMouseX = e.getX();
            currentMouseY = e.getY();
	
	    // Clicked in the Thumb area?
	    if(getThumbBounds().contains(currentMouseX, currentMouseY))	{
                switch (scrollbar.getOrientation()) {
                case JScrollBar.VERTICAL:
		    offset = currentMouseY - getThumbBounds().y;
                    break;
                case JScrollBar.HORIZONTAL:
		    offset = currentMouseX - getThumbBounds().x;
                    break;
                }
		isDragging = true;
		return;
	    }
	    else if (getSupportsAbsolutePositioning() &&
		     SwingUtilities.isMiddleMouseButton(e)) {
                switch (scrollbar.getOrientation()) {
                case JScrollBar.VERTICAL:
		    offset = getThumbBounds().height / 2;
                    break;
                case JScrollBar.HORIZONTAL:
		    offset = getThumbBounds().width / 2;
                    break;
                }
		isDragging = true;
		setValueFrom(e);
		return;
	    }
	    isDragging = false;
							
            Dimension sbSize = scrollbar.getSize();
            direction = +1;

            switch (scrollbar.getOrientation()) {
            case JScrollBar.VERTICAL:
                if (getThumbBounds().isEmpty()) {
                    int scrollbarCenter = sbSize.height / 2;
		    direction = (currentMouseY < scrollbarCenter) ? -1 : +1;
                } else {
                    int thumbY = getThumbBounds().y;
		    direction = (currentMouseY < thumbY) ? -1 : +1;
                }
                break;                    
            case JScrollBar.HORIZONTAL:
                if (getThumbBounds().isEmpty()) {
                    int scrollbarCenter = sbSize.width / 2;
                    direction = (currentMouseX < scrollbarCenter) ? -1 : +1;
                } else {
                    int thumbX = getThumbBounds().x;
                    direction = (currentMouseX < thumbX) ? -1 : +1;
                }
		if (!scrollbar.getComponentOrientation().isLeftToRight()) {
		    direction = -direction;
		}
                break;
            }
	    scrollByBlock(direction);

	    scrollTimer.stop();
	    scrollListener.setDirection(direction);
	    scrollListener.setScrollByBlock(true);
	    startScrollTimerIfNecessary();
        }
		

        /** 
	 * Set the models value to the position of the thumb's top of Vertical
	 * scrollbar, or the left/right of Horizontal scrollbar in
	 * left-to-right/right-to-left scrollbar relative to the origin of the
	 * track.
	 */
	public void mouseDragged(MouseEvent e) {
	    if (SwingUtilities.isRightMouseButton(e) ||
		(!getSupportsAbsolutePositioning() &&
		 SwingUtilities.isMiddleMouseButton(e)))
		return;
	    if(!scrollbar.isEnabled() || getThumbBounds().isEmpty()) {
		return;
	    }
	    if (isDragging) {
		setValueFrom(e);
	    } else {
		currentMouseX = e.getX();
		currentMouseY = e.getY();
                updateThumbState(currentMouseX, currentMouseY);
		startScrollTimerIfNecessary();
	    }
	}

	private void setValueFrom(MouseEvent e) {
            boolean active = isThumbRollover();
	    BoundedRangeModel model = scrollbar.getModel();
	    Rectangle thumbR = getThumbBounds();
	    float trackLength;
	    int thumbMin, thumbMax, thumbPos;
	    
	    if (scrollbar.getOrientation() == JScrollBar.VERTICAL) {
		thumbMin = trackRect.y;
		thumbMax = trackRect.y + trackRect.height - thumbR.height;
		thumbPos = Math.min(thumbMax, Math.max(thumbMin, (e.getY() - offset)));
		setThumbBounds(thumbR.x, thumbPos, thumbR.width, thumbR.height);
		trackLength = getTrackBounds().height;
	    }
	    else {
		    thumbMin = trackRect.x;
		    thumbMax = trackRect.x + trackRect.width - thumbR.width;
		    thumbPos = Math.min(thumbMax, Math.max(thumbMin, (e.getX() - offset)));
		    setThumbBounds(thumbPos, thumbR.y, thumbR.width, thumbR.height);
		    trackLength = getTrackBounds().width;
	    }
	    
	    /* Set the scrollbars value.  If the thumb has reached the end of
	     * the scrollbar, then just set the value to its maximum.  Otherwise
	     * compute the value as accurately as possible.
	     */
	    if (thumbPos == thumbMax) {
		if (scrollbar.getOrientation() == JScrollBar.VERTICAL || 
		    scrollbar.getComponentOrientation().isLeftToRight()) {
		    scrollbar.setValue(model.getMaximum() - model.getExtent());
		} else {
		    scrollbar.setValue(model.getMinimum());
		}
	    }
	    else {
		float valueMax = model.getMaximum() - model.getExtent();
		float valueRange = valueMax - model.getMinimum();
		float thumbValue = thumbPos - thumbMin;
		float thumbRange = thumbMax - thumbMin;
		int value;
		if (scrollbar.getOrientation() == JScrollBar.VERTICAL || 
		    scrollbar.getComponentOrientation().isLeftToRight()) {
		    value = (int)(0.5 + ((thumbValue / thumbRange) * valueRange));
		} else {
		    value = (int)(0.5 + (((thumbMax - thumbPos) / thumbRange) * valueRange));
		}

		useCachedValue = true;
		scrollBarValue = value + model.getMinimum();
		scrollbar.setValue(adjustValueIfNecessary(scrollBarValue));
	    }
            setThumbRollover(active);
	}

	private int adjustValueIfNecessary(int value) {
	    if (scrollbar.getParent() instanceof JScrollPane) {
		JScrollPane scrollpane = (JScrollPane)scrollbar.getParent();
		JViewport viewport = scrollpane.getViewport();
		Component view = viewport.getView();
		if (view instanceof JList) {
		    JList list = (JList)view;
		    if (DefaultLookup.getBoolean(list, list.getUI(),
						 "List.lockToPositionOnScroll", false)) {
			int adjustedValue = value;
			int mode = list.getLayoutOrientation();
			int orientation = scrollbar.getOrientation();
			if (orientation == JScrollBar.VERTICAL && mode == JList.VERTICAL) {
			    int index = list.locationToIndex(new Point(0, value));
			    Rectangle rect = list.getCellBounds(index, index);
			    if (rect != null) {
				adjustedValue = rect.y;
			    }
			}
			if (orientation == JScrollBar.HORIZONTAL &&
			    (mode == JList.VERTICAL_WRAP || mode == JList.HORIZONTAL_WRAP)) {
			    if (scrollpane.getComponentOrientation().isLeftToRight()) {
				int index = list.locationToIndex(new Point(value, 0));
				Rectangle rect = list.getCellBounds(index, index);
				if (rect != null) {
				    adjustedValue = rect.x;
				}
			    }
			    else {
				Point loc = new Point(value, 0);
				int extent = viewport.getExtentSize().width;
				loc.x += extent - 1;
				int index = list.locationToIndex(loc);
				Rectangle rect = list.getCellBounds(index, index);
				if (rect != null) {
				    adjustedValue = rect.x + rect.width - extent;
				}
			    }
			}
			value = adjustedValue;
			
		    }
		}
	    }
	    return value;
	}

	private void startScrollTimerIfNecessary() {
	    if (scrollTimer.isRunning()) {
		return;
	    }
            
            Rectangle tb = getThumbBounds();
            
	    switch (scrollbar.getOrientation()) {
	    case JScrollBar.VERTICAL:
		if (direction > 0) {
                    if (tb.y + tb.height < trackListener.currentMouseY) {
			scrollTimer.start();
		    }
                } else if (tb.y > trackListener.currentMouseY) {
		    scrollTimer.start();
		}
		break;
	    case JScrollBar.HORIZONTAL:
                if ((direction > 0 && isMouseAfterThumb())
                        || (direction < 0 && isMouseBeforeThumb())) {

                    scrollTimer.start();
		}
		break;
	    }
	}
		
	public void mouseMoved(MouseEvent e) {
            if (!isDragging) {
                updateThumbState(e.getX(), e.getY());
            }
	}

        /**
         * Invoked when the mouse exits the scrollbar.
         *
         * @param e MouseEvent further describing the event
         * @since 1.5
         */
        public void mouseExited(MouseEvent e) {
            if (!isDragging) {
                setThumbRollover(false);
            }
        }
    }
        

    /**
     * Listener for cursor keys.
     */
    protected class ArrowButtonListener extends MouseAdapter
    {		
	// Because we are handling both mousePressed and Actions
	// we need to make sure we don't fire under both conditions.
	// (keyfocus on scrollbars causes action without mousePress
	boolean handledEvent;
	
	public void mousePressed(MouseEvent e)		{
	    if(!scrollbar.isEnabled()) { return; }
	    // not an unmodified left mouse button
	    //if(e.getModifiers() != InputEvent.BUTTON1_MASK) {return; }
	    if( ! SwingUtilities.isLeftMouseButton(e)) { return; }

	    int direction = (e.getSource() == incrButton) ? 1 : -1;
		
	    scrollByUnit(direction);
	    scrollTimer.stop();
	    scrollListener.setDirection(direction);
	    scrollListener.setScrollByBlock(false);
	    scrollTimer.start();

	    handledEvent = true;	
	    if (!scrollbar.hasFocus() && scrollbar.isRequestFocusEnabled()) {
		scrollbar.requestFocus();
	    }
	}

	public void mouseReleased(MouseEvent e)		{
	    scrollTimer.stop();
	    handledEvent = false;
	    scrollbar.setValueIsAdjusting(false);
	}
    }


    /**
     * Listener for scrolling events initiated in the
     * <code>ScrollPane</code>.
     */
    protected class ScrollListener implements ActionListener
    {
	int direction = +1;
	boolean useBlockIncrement;

	public ScrollListener()	{
	    direction = +1;
	    useBlockIncrement = false;
	}

        public ScrollListener(int dir, boolean block)	{
	    direction = dir;
	    useBlockIncrement = block;
	}
	
	public void setDirection(int direction) { this.direction = direction; }
	public void setScrollByBlock(boolean block) { this.useBlockIncrement = block; }
					
	public void actionPerformed(ActionEvent e) {
	    if(useBlockIncrement)	{
		scrollByBlock(direction);		
		// Stop scrolling if the thumb catches up with the mouse
		if(scrollbar.getOrientation() == JScrollBar.VERTICAL)	{
		    if(direction > 0)	{
			if(getThumbBounds().y + getThumbBounds().height 
				>= trackListener.currentMouseY)
				    ((Timer)e.getSource()).stop();
		    } else if(getThumbBounds().y <= trackListener.currentMouseY)	{
			((Timer)e.getSource()).stop();
		    }
		} else {
                    if ((direction > 0 && !isMouseAfterThumb())
                           || (direction < 0 && !isMouseBeforeThumb())) {

                       ((Timer)e.getSource()).stop();
		    }
	        }
	    } else {
		scrollByUnit(direction);
	    }

	    if(direction > 0 
		&& scrollbar.getValue()+scrollbar.getVisibleAmount() 
			>= scrollbar.getMaximum())
		((Timer)e.getSource()).stop();
	    else if(direction < 0 
		&& scrollbar.getValue() <= scrollbar.getMinimum())
	        ((Timer)e.getSource()).stop();
	}
    }

    private boolean isMouseLeftOfThumb() {
        return trackListener.currentMouseX < getThumbBounds().x;
    }

    private boolean isMouseRightOfThumb() {
        Rectangle tb = getThumbBounds();
        return trackListener.currentMouseX > tb.x + tb.width;
    }

    private boolean isMouseBeforeThumb() {
        return scrollbar.getComponentOrientation().isLeftToRight()
            ? isMouseLeftOfThumb()
            : isMouseRightOfThumb();
    }
    
    private boolean isMouseAfterThumb() {
        return scrollbar.getComponentOrientation().isLeftToRight()
            ? isMouseRightOfThumb()
            : isMouseLeftOfThumb();
    }

    private void updateButtonDirections() {
        int orient = scrollbar.getOrientation();
        if (scrollbar.getComponentOrientation().isLeftToRight()) { 
            if (incrButton instanceof BasicArrowButton) {
                ((BasicArrowButton)incrButton).setDirection(
                        orient == HORIZONTAL? EAST : SOUTH);
            }
            if (decrButton instanceof BasicArrowButton) {
                ((BasicArrowButton)decrButton).setDirection(
                        orient == HORIZONTAL? WEST : NORTH);
            }
        }
        else {
            if (incrButton instanceof BasicArrowButton) {
                ((BasicArrowButton)incrButton).setDirection(
                        orient == HORIZONTAL? WEST : SOUTH);
            }
            if (decrButton instanceof BasicArrowButton) {
                ((BasicArrowButton)decrButton).setDirection(
                        orient == HORIZONTAL ? EAST : NORTH);
            }
        }
    }

    public class PropertyChangeHandler implements PropertyChangeListener 
    {
        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

        public void propertyChange(PropertyChangeEvent e) {
            getHandler().propertyChange(e);
	}
    }


    /**
     * Used for scrolling the scrollbar.
     */
    private static class Actions extends UIAction {
        private static final String POSITIVE_UNIT_INCREMENT =
                                    "positiveUnitIncrement";
        private static final String POSITIVE_BLOCK_INCREMENT =
                                    "positiveBlockIncrement";
        private static final String NEGATIVE_UNIT_INCREMENT =
                                    "negativeUnitIncrement";
        private static final String NEGATIVE_BLOCK_INCREMENT =
                                    "negativeBlockIncrement";
        private static final String MIN_SCROLL = "minScroll";
        private static final String MAX_SCROLL = "maxScroll";

        Actions(String name) {
            super(name);
        }

        public void actionPerformed(ActionEvent e) {
	    JScrollBar scrollBar = (JScrollBar)e.getSource();
            String key = getName();
            if (key == POSITIVE_UNIT_INCREMENT) {
                scroll(scrollBar, POSITIVE_SCROLL, false);
            }
            else if (key == POSITIVE_BLOCK_INCREMENT) {
                scroll(scrollBar, POSITIVE_SCROLL, true);
            }
            else if (key == NEGATIVE_UNIT_INCREMENT) {
                scroll(scrollBar, NEGATIVE_SCROLL, false);
            }
            else if (key == NEGATIVE_BLOCK_INCREMENT) {
                scroll(scrollBar, NEGATIVE_SCROLL, true);
            }
            else if (key == MIN_SCROLL) {
                scroll(scrollBar, BasicScrollBarUI.MIN_SCROLL, true);
            }
            else if (key == MAX_SCROLL) {
                scroll(scrollBar, BasicScrollBarUI.MAX_SCROLL, true);
            }
        }
        private void scroll(JScrollBar scrollBar, int dir, boolean block) {

	    if (dir == NEGATIVE_SCROLL || dir == POSITIVE_SCROLL) {
		int amount;
		// Don't use the BasicScrollBarUI.scrollByXXX methods as we
		// don't want to use an invokeLater to reset the trackHighlight
		// via an invokeLater
		if (block) {
		    if (dir == NEGATIVE_SCROLL) {
			amount = -1 * scrollBar.getBlockIncrement(-1);
		    }
		    else {
			amount = scrollBar.getBlockIncrement(1);
		    }
		}
		else {
		    if (dir == NEGATIVE_SCROLL) {
			amount = -1 * scrollBar.getUnitIncrement(-1);
		    }
		    else {
			amount = scrollBar.getUnitIncrement(1);
		    }
		}
		scrollBar.setValue(scrollBar.getValue() + amount);
	    }
	    else if (dir == BasicScrollBarUI.MIN_SCROLL) {
		scrollBar.setValue(scrollBar.getMinimum());
	    }
	    else if (dir == BasicScrollBarUI.MAX_SCROLL) {
		scrollBar.setValue(scrollBar.getMaximum());
	    }
	}
    }


    //
    // EventHandler
    //
    private class Handler implements FocusListener, PropertyChangeListener {
        //
        // FocusListener
        //
        public void focusGained(FocusEvent e) {
            scrollbar.repaint();
        }

        public void focusLost(FocusEvent e) {
            scrollbar.repaint();
        }


        //
        // PropertyChangeListener
        //
        public void propertyChange(PropertyChangeEvent e) {
	    String propertyName = e.getPropertyName();

	    if ("model" == propertyName) {
	        BoundedRangeModel oldModel = (BoundedRangeModel)e.getOldValue();
	        BoundedRangeModel newModel = (BoundedRangeModel)e.getNewValue();
		oldModel.removeChangeListener(modelListener);
		newModel.addChangeListener(modelListener);
		scrollbar.repaint();
		scrollbar.revalidate();
	    } else if ("orientation" == propertyName) {
                updateButtonDirections();
            } else if ("componentOrientation" == propertyName) {
                updateButtonDirections();
                InputMap inputMap = getInputMap(JComponent.WHEN_FOCUSED);
                SwingUtilities.replaceUIInputMap(scrollbar, JComponent.WHEN_FOCUSED, inputMap);
            }
        }
    }
}
            
            
